1. Field of the Invention
The invention relates in general to a wireless network apparatus, and more particularly to a wireless network apparatus and an adaptive digital beamforming method thereof.
2. Description of the Related Art
Given the increasing demand for high data rate traffic, the need for very efficient wireless data communication systems has become increasingly important. Smart antenna systems have therefore been proposed with beamforming techniques for decreasing interferences and overcoming signal fading due to multipath propagations.
FIG. 1 shows architecture of an archetypical smart antenna system equipped with analog beamformers. The smart antenna system 100 has an antenna array 110 with n+1 antennae capable of generating a multi-beam pattern 112. Signals from remote units (not shown), such as from network clients, that are each assigned with a distinct media access control (MAC) ID, MAC101-n, are then detected and received by the antenna array when falling within a coverage area defined by the beam pattern. An analog beamformer 120 is then arranged to “weight” the incoming signals, i.e. to apply appropriate phase shifting and amplitude scaling such that the incoming signals are reconstructed. The weight adjusted incoming signals are provided to transceiver 130, which filter the signals. The filtered signals from the transceiver 130 are provided to an AD/DA converter 140 to convert the filtered signals into digital format. The converted digital signals are then provided to a MAC device 150.
However, conventional smart antenna systems equipped with analog beamformers require a complex architecture and consumes considerable power, and is therefore not suitable for compact portable network-capable devices.